v3.26.3
Fair value measurement (Tables)
 6 Months Ended
Sep. 30, 2026
Fair Value Measurement [Abstract]  
Schedule of fair value measurement of assets The following table categorises these assets and liabilities by the valuation methodology applied in determining their fair value using the fair value hierarchy described on page 203 of the Annual Report and Accounts for the year ended 31 March 2026.
30 September 202631 March 2026
Level 1
£m		Level 2
£m		Level 3
£m		Total
£m		Level 1
£m		Level 2
£m		Level 3
£m		Total
£m
Assets
Investments held at fair value through profit and loss2,341 — 1,637 3,978 1,914 — 450 2,364 
Investments held at fair value through other comprehensive income1
— 374 — 374 — 385 — 385 
Financing derivatives— 551 21 572 — 691 26 717 
Commodity contract derivatives— 134 14 148 — 111 10 121 
2,341 1,059 1,672 5,072 1,914 1,187 486 3,587 
Liabilities
Financing derivatives— (1,231)(41)(1,272)— (864)(86)(950)
Commodity contract derivatives— (90)(23)(113)— (55)(13)(68)
— (1,321)(64)(1,385)— (919)(99)(1,018)
Total2,341 (262)1,608 3,687 1,914 268 387 2,569 
1.Investments held include instruments which meet the criteria of IFRS 9 or IAS 19.
The changes in fair value of our level 3 financial assets and liabilities in the six months to 30 September are presented below:
Financing derivativesCommodity contract derivatives
Other1
Total
20262025202620252026202520262025
£m£m£m£m£m£m£m£m
At 1 April(60)(64)(3)(20)450 407 387 323 
Net (losses)/gains through the consolidated income statement for the period2,3
(3)3 (6)72 197 (9)188 66 
Purchases— — — — 1,097 9 1,097 9 
Settlements43 — — (12)(107)(1)(64)(13)
At 30 September
(20)(61)(9)40 1,637 406 1,608 385 
1.Other comprises our investments in Joulent LLC, Sunrun Neptune 2016 LLC and the investments made by National Grid Partners, which are accounted for at fair value through profit and loss.
2.Losses of £7 million (2025: gains of £3 million) are attributable to derivative financial instruments held at the end of the reporting period and have been recognised in finance costs in the consolidated income statement. 
3.Losses of £6 million (2025: gains of £72 million) are attributable to the commodity contract derivative financial instruments held at the end of the reporting period and have been recognised in other operating costs in the consolidated income statement.
Schedule of impacts of reasonably possible changes in significant Level 3 assumptions
The impacts on a post-tax basis of reasonably possible changes in significant assumptions used in valuing assets and liabilities classified within Level 3 of the fair value hierarchy are as follows:
Financing derivativesCommodity contract derivativesOther
Six months ended 30 September202620252026202520262025
£m£m£m£m£m£m
10% increase in commodity prices— — 20 3 — — 
10% decrease in commodity prices— — (20)(2)— — 
+10% market area price change— — 13 1 — — 
-10% market area price change— — (15)(2)— — 
+20 basis point increase in Limited Price Index
(LPI) market curve		(12)(32)— — — — 
-20 basis point decrease in LPI market curve12 30 — — — — 
+20 basis point increase between Retail Price Index (RPI) and Consumer Price Index (CPI)24 29 — — — — 
-20 basis point decrease between RPI and CPI(23)(27)— — — — 
+100 basis points change in discount rate— — — — (6)(6)
-100 basis points change in discount rate— — — — 7 7 
+10% change in venture capital price— — — — 107 26 
-10% change in venture capital price¹— — — — (107)(26)
1.A decrease in venture capital price may also result in losses recognised on the committed further capital contributions to Joulent LLC.
Schedule of fair value measurement of liabilities The following table categorises these assets and liabilities by the valuation methodology applied in determining their fair value using the fair value hierarchy described on page 203 of the Annual Report and Accounts for the year ended 31 March 2026.
30 September 202631 March 2026
Level 1
£m		Level 2
£m		Level 3
£m		Total
£m		Level 1
£m		Level 2
£m		Level 3
£m		Total
£m
Assets
Investments held at fair value through profit and loss2,341 — 1,637 3,978 1,914 — 450 2,364 
Investments held at fair value through other comprehensive income1
— 374 — 374 — 385 — 385 
Financing derivatives— 551 21 572 — 691 26 717 
Commodity contract derivatives— 134 14 148 — 111 10 121 
2,341 1,059 1,672 5,072 1,914 1,187 486 3,587 
Liabilities
Financing derivatives— (1,231)(41)(1,272)— (864)(86)(950)
Commodity contract derivatives— (90)(23)(113)— (55)(13)(68)
— (1,321)(64)(1,385)— (919)(99)(1,018)
Total2,341 (262)1,608 3,687 1,914 268 387 2,569 
1.Investments held include instruments which meet the criteria of IFRS 9 or IAS 19.
The changes in fair value of our level 3 financial assets and liabilities in the six months to 30 September are presented below:
Financing derivativesCommodity contract derivatives
Other1
Total
20262025202620252026202520262025
£m£m£m£m£m£m£m£m
At 1 April(60)(64)(3)(20)450 407 387 323 
Net (losses)/gains through the consolidated income statement for the period2,3
(3)3 (6)72 197 (9)188 66 
Purchases— — — — 1,097 9 1,097 9 
Settlements43 — — (12)(107)(1)(64)(13)
At 30 September
(20)(61)(9)40 1,637 406 1,608 385 
1.Other comprises our investments in Joulent LLC, Sunrun Neptune 2016 LLC and the investments made by National Grid Partners, which are accounted for at fair value through profit and loss.
2.Losses of £7 million (2025: gains of £3 million) are attributable to derivative financial instruments held at the end of the reporting period and have been recognised in finance costs in the consolidated income statement. 
3.Losses of £6 million (2025: gains of £72 million) are attributable to the commodity contract derivative financial instruments held at the end of the reporting period and have been recognised in other operating costs in the consolidated income statement.